1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor laser device which can be used in an optical communication system, a bar code reader, and the like.
2. Description of the Related Art
In a prior art method for manufacturing a laser semiconductor device, an N-type cladding layer, an active layer, and a P-type cladding layer are grown by a liquid phase epitaxial (LPE) growth method on an N-type substrate. Then, striped grooves are formed in the N-type cladding layer, the active layer and the P-type cladding layer on both sides of a light emission area. Then, a P-type layer and an N-type layer are buried in the P-type cladding layer except for the light emission area, to prevent a current from flowing therethrough. This increases a current flowing through the active layer. This will be explained later in detail.
In the prior art manufacturing method, however, the P-type layer and the N-type layer acting as current blocking layers are so thin at the outer edges of the striped grooves that the current blocking layers are disconnected therein. This invites a leakage current. Also, the resistance of the current blocking layers is reduced, which reduces the current flowing through the active layer. Thus, the prior art manufacturing method reduces the reliability of operation, thus reducing the manufacturing yield of semiconductor laser devices.